Part I Effect of Immune Serum and Complement on O(2) Uptake Using the 3 strains of Vibrio cholera, original strain (INABA's strain), intermediate variant strain (HIKOZIMA's strain) and variant strain (OGAWA's strain), the author studied the effect of immune serum and complement on O(2)uptake of the resting cells of these microorganism. Immune serum was added into the resting cell suspension, in which complement was added in an experiment and was not in another experiment, in a various concentration with substrate. And obtained the following results 1) With absence of complement O(2) uptake was inhibited to a slight degree by the addition of immune serum. The inhibition was increased. carrespondingly with the concentration of the serum This findings was supposedly due to the agglutination of bacteria by the action of the immune serum. 2) In the presence of complement, O(2) uptake was also inhibited by the addition of immune serum; especially, strongly inhibited at a low concentration of that, i.e. in dilutions of 1:300-1:400. The inhibition was supposed to be arisen from the lesion on the cells being to be bacteriolysis shertly after that. Part Ⅱ Enzyme Activities Affectad by Bacteriolysis Using the 3 strains of Vibrio cholera as in the part I, the author observed the changes on the enzyme activities of the bacterial cells by affecting the cells by means of suspension into various media or immune reaction. The following results were obtained. 1) The enzyme activities were not so decreased by the washing of the cells with saline added phosphate buffer. But the activities and the numbers of surviving cells were markedly decreased in the case of the washing with saline unadded phosphate buffer, saline solution or distilled water. 2) The enzyme activities were decrealed proportionally to the affection time of immune serum and complement, and eventually qacteriolysis occured. This finding was most distinctive in dilutions of 1:100-1:300 of serum. 3) The decrease of oxidation capacity by bacteriolysis was differ in the substrate oxydized. That was very prominient in the case of glucose, pyruvate and aspartate, while that was rather slight at the oxidation of lactate, succinate and cysteine, and the presence of the oxidation capacities was also found in the centrifuged supernatant of bacteriolysed cells. 4) The deaminative and the desulfhydrative abilities for cysteine were retained after the lysis of bacteria, but these for formation of indol were not found at that state.